Wednesday, February 08, 2017Register
 Species Spotlight

[Photo: Tom Brennan, Reptiles of Arizona]
[Photo: Tom Brennan, Reptiles of Arizona]

Round-tailed Horned Lizard
Phrynosoma modestum

Description: The round-tailed horned lizard is a small, flat and wide lizard approximately 2.75 inches (7 cm) long, not including its short tail, and up to 4 inches (10 cm) long in total. The coloration of this lizard is variable ranging from light gray to brown and pale yellow to reddish brown. The underbelly is pale yellow or white. The lizard has pairs of dark spots on its neck, groin and base of tail. This lizard has four short spines on the back of its head.

Life History: The round-tailed lizard lays one to two clutches of 6-19 eggs from May through July. Hatchlings emerge in July. These lizards feed on ants, termites, beetles, butterflies and moth larvae. Round-tailed lizards are ground dwellers which are active in the mid-morning. These lizards hibernate during late fall and winter. Round-tailed lizards lie flat and motionless when threatened and their mottled grayish coloration provides excellent camouflage in the desert habitat.

Habitat: The habitat of this lizard is the sandy, arid to semi-arid climates of the Chihuahuahn desertscrub and grasslands. It prefers sunny areas with gravelly or rocky soil.

Distribution: Phrynosoma modestum is found in eastern Arizona, west Texas and the Texas panhandle, and northern Mexico.


Herps of Texas - Lizards

Reptiles of Arizona - Round-tailed Lizard

 Upper Gila Mountains

Upper Gila Mountains Level 3 & 4 Ecoregions Map [Figure: Houston Advanced Research Center using USEPA data]
Upper Gila Mountains Level 3 & 4 Ecoregions Map [Figure: Houston Advanced Research Center using USEPA data]

The Upper Gila Mountains stretches from northwestern Arizona into western and central New Mexico, with disjunct areas in southeastern New Mexico and a small part of west Texas. This ecoregion can be broadly described as the Arizona/New Mexico Mountains.

Elevations in this area range from 4,500-10,000 feet (1,370-3,000 m).  At lower elevations (below 5500 feet or 1680 meters) vegetation appears as a continuation of the surrounding desert habitat with juniper, yucca, stool, lechuguilla, ocotillo, mesquite and prickly pear cactus growing over underlying limestone, shale and sandstone. At elevations above 5500 feet (up to 8700 feet or 2650 meters), vegetation changes to chaparral-type with desert ceanothus, alderleaf mountain mahogany, and catclaw mimosa present. At higher elevations, semi-arid grassland areas dominate, and at the highest elevations, Douglas-fir, southwestern white pine, and ponderosa pine can be found.

The ecoregion is generally arid, receiving only 10-35 inches (25-88 cm) of precipitation per year; although freshwater springs emerge from the underlying limestone and create oases of riparian woodland with species such as velvet ash, chinkapin oak, Texas madrone, bigtooth maple, maidenhair fern and sawgrass present. Wildlife common to this ecoregion are: coyote, mountain lion, bobcat, badger, mule deer, javelinas, Texas banded gecko, western diamondback rattlesnake, bullsnake, round-tailed horned lizard, elk, black bear, gray foxes, and striped and hog-nosed skunks. The major land uses in this area are ranching, recreation, forestry, mining, public forests and tribal lands. Historical overgrazing may have led to the conversion of low elevation grasslands to the desert shrubs that exist there today.

 Invasive Spotlight

[Photo: Steve Dewey, Utah State University,]
[Photo: Steve Dewey, Utah State University,]

Tamarix ramosissima

Description: Saltcedar is a deciduous shrub or small tree in the Tamarisk family, which grows from 5-30 feet (1.5-9 m) tall. This species forms dense thickets of slender stems which are reddish to orange in color when young and change to gray as the species matures. Leaves are grayish green, compound and alternate, and 1/16 of an inch (16 mm) in length. Flowers are in dense masses of pale pink or white blossoms and bloom from March through September. Seeds are tiny, only 1/25 inch (10 mm) in diameter. This species has very long tap roots.

Life History: Saltcedars produced both vegetatively, via sprouting, and sexually. The flowers produce thousands of seeds in small capsules, which are dispersed by wind and water.

Habitat: Saltcedar grows in or near streams, waterways, bottomlands, moist pastures, and drainage washes in both disturbed and undisturbed habitats. This plant can tolerate highly saline (up to 15,000 ppm of salt) and alkaline conditions.

Distribution: Tamarix ramosissima is prevalent throughout the Southwest and is also located in the Central Southwest including Texas, Louisiana, Arkansas and Louisiana.

Status: Saltcedars disrupt the natural hydrology of ecosystems. This species has long tap roots which it uses to suck up water from the water table. This species also interrupts flow regimes of surface waters. Because this species often grows in semi-arid to arid environments, the competition for water is fierce. Saltcedar disrupts the water cycle required by native plant and wildlife communities. This disruption causes greater intensity of floods and fires in these ecosystems. Combinations of biological, mechanical and chemical methods are the most effective way to manage for saltcedar.


Plant Conservation Alliance

US Forest Service Weed of the Week

 Endangered Spotight

[Photo: Natural Heritage New Mexico, U of New Mexico]
[Photo: Natural Heritage New Mexico, U of New Mexico]

Mexican Spotted Owl
Strix occidentalis lucida

Description: The Mexican spotted owl is a large owl with mottled white and brown feathers. It has dark eyes and a brown tail with thin white banding. The owl is 16-19 inches (41-48 cm) long, has a 42-45 inch (107-114 cm) wing span, and weighs 19.5-23 ounces (547-647 grams). Mexican spotted owls are sexually dimorphic with females larger than males.

Life History: Mating occurs in March and females lay 1-3 eggs in late March or early April. Incubation lasts 30 days and eggs usually hatch in early May. Owlets will leave the nest 35 days after hatching, and by October, will disperse from their parents. Mexican spotted owls locate prey from perches and pounce on them using their talons. These owls eat woodrats, mice, voles, rabbits, gophers, bats, birds, reptiles and insects.

Habitat: The Mexican spotted owl prefers high elevation, old-growth forests of white pine, Douglas fir and ponderosa pine. Optimal habitat consists of steep slopes and rocky cliffs.

Distribution: Strix occidentals lucida is found in Arizona, New Mexico, west Texas, and south to central Mexico. In Texas, the Mexican spotted owl can only be found in the Davis and Guadalupe Mountains.

Status: The Mexican spotted owl is a state and federally listed threatened species (1993). Loss of habitat due to harvesting of old-growth timber stands has caused the decline of this species. This species is protected within the Guadalupe Mountains National Park and on Nature Conservancy lands within the Davis Mountains.


US Fish and Wildlife Service - Mexican Spotted Owl

TX Parks and Wildlife - Mexican Spotted Owl

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